Modest mutations convert human TfR1 into an efficient receptor for AMAV and TCRV.
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Abstract
<p>(A) The structure of the human TfR1 dimer is shown, oriented with the cell membrane at the bottom. The apical, protease-like, and helical domains are indicated in green, red, and yellow, respectively, on one monomer. The other monomer is shown in cyan. In the right panel, the TfR1 apical domain is enlarged; a loop comprising residues 202-212, implicated as a site of interaction with the GPs of NW clade B arenaviruses, is shown. The side chains of residues D204, K205, R208, V210, and Y211 are colored yellow. The image was rendered using PyMol <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1000358#ppat.1000358-DeLano1" target="_blank">[59]</a>. (B) Sequence alignment of residues 195 through 216 of human TfR1 with analogous sequences of the TfR1 orthologs of <i>Z. brevicauda</i> (ZbTfR1), <i>A. jamaicensis</i> (AjTfR1), and <i>N. spinosus</i> (NsTfR1). Variants of human TfR1 containing sequence from <i>Z. brevicauda</i> (zh1 and zh2), <i>A. jamaicensis</i> (ah2 through ah5), and <i>N. spinosus</i> (nh2, nh4, nh5, nh7, and nh8) TfR1 were generated based on this sequence alignment. Zb, Aj, and NsTfR1 sequences are shown in green, blue, and yellow, respectively. The right panel summarizes the entry data. ND = not determined. (C–E) HEK293T cells were transfected with plasmids encoding human, Zb, Aj, or NsTfR1 along with the zh variants (C), the ah variants (D), or the nh variants (E). The expression level of each TfR1 variant was assessed as in <a href="http://www.plospathogens.org/article/info:doi/10.1371/journal.ppat.1000358#ppat-1000358-g003" target="_blank">Figure 3</a>. In parallel, cells were infected with AMAV, TCRV, or VSV pseudoviruses. The expression levels of the various TfR1 orthologs were normalized to that of human TfR1 (α-flag, left panels), and infection levels were normalized to that of mock-transfected cells.</p